NuGet auto package restore does not work with MSBuild

Nuget's Automatic Package Restore is a feature of the Visual Studio (starting in 2013), not MSBuild. You'll have to run nuget.exe restore if you want to restore packages from the command line.

You can also use the Enable Nuget Package Restore feature, but this is no longer recommended by the nuget folks because it makes intrusive changes to the project files and may cause problems if you build those projects in another solution.

If you are using Visual Studio 2017 or later which ships with MSBuild 15 or later, and your .csproj files are in the new PackageReference format, the simplest method is to use the new MSBuild Restore target.

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No-one has actually answered the original question, which is "how do I get NuGet packages to auto-restore when building from the command-line with MSBuild?" The answer is: unless you are using the "Enable NuGet package restore" option (which is now deprecated as per this reference), you can't (but see below). If you are trying to do e.g. automated builds on a CI server, this sucks.

However there is a slightly roundabout way to get the desired behaviour:

1. Download the latest NuGet executable from https://dist.nuget.org/win-x86-commandline/latest/nuget.exe and place it somewhere in your PATH. (You can do this as a pre-build step.)
2. Run nuget restore which will auto-download all the missing packages.
3. Run msbuild to build your solution.

Aside: while the new and recommended way to do auto package restore involves less clutter in your version control, it also makes command-line package restore impossible unless you jump through the extra hoop of downloading and running nuget.exe. Progress?